2014 sierra 5.3 questions about active fuel management

Tonycal · July 10, 2022

So I have a 2014 sierra 1500 with a 5.3 L. I put a super chip programmer on it so I can program it for a better fuel mileage I am getting around 22 mpg gallons to 24 mpg on the highway now . A few people have told me that the active fuel management when it goes into V4 mode it doesn’t put oil to the lifters on the cylinders that are not firing so it makes lifters collapse which ruins the whole cylinder head and sometimes can ruin the piston. I was wondering if anybody knows if any of this is true also I know my programmer turns off the active fuel management but I was wondering how much does it actually improve fuel mileage? Is it a good or bad idea to shut it off? Well my engine actually last a lot longer and will I be guaranteed do not have any lifter issues if I turn it off? Any advice would be greatly appreciated. The thing is I don’t want to ruin my engine but I also want to get the best mileage per gallon as possible.

DominatorZ71 · July 10, 2022

56 minutes ago, Tonycal said:

So I have a 2014 sierra 1500 with a 5.3 L. I put a super chip programmer on it so I can program it for a better fuel mileage I am getting around 22 mpg gallons to 24 mpg on the highway now . A few people have told me that the active fuel management when it goes into V4 mode it doesn’t put oil to the lifters on the cylinders that are not firing so it makes lifters collapse which ruins the whole cylinder head and sometimes can ruin the piston. I was wondering if anybody knows if any of this is true also I know my programmer turns off the active fuel management but I was wondering how much does it actually improve fuel mileage? Is it a good or bad idea to shut it off? Well my engine actually last a lot longer and will I be guaranteed do not have any lifter issues if I turn it off? Any advice would be greatly appreciated. The thing is I don’t want to ruin my engine but I also want to get the best mileage per gallon as possible.

It is 100% true and the difference might be 1 or 2 MPG. Definitely not worth catastrophic engine failure. I have a 2016 Silverado and a 2017 Tahoe and both AFM systems are disabled through a tuner. Truck MPG is irrelevant because it's on 35s and is not setup for economy. The Tahoe I work out of however still gets a high of 27 mpg highway and a low of 20 MPG city. Definitely save yourself the headache and disable that

steelerdude15 · July 11, 2022

Your truck will run better too with it turned off. You won’t have to deal with that sputter when it goes from V4 mode to V8 mode.

Grumpy Bear · July 11, 2022

1 hour ago, Tonycal said:

So I have a 2014 sierra 1500 with a 5.3 L. I put a super chip programmer on it so I can program it for a better fuel mileage I am getting around 22 mpg gallons to 24 mpg on the highway now . A few people have told me that the active fuel management when it goes into V4 mode it doesn’t put oil to the lifters on the cylinders that are not firing so it makes lifters collapse which ruins the whole cylinder head and sometimes can ruin the piston. I was wondering if anybody knows if any of this is true also I know my programmer turns off the active fuel management but I was wondering how much does it actually improve fuel mileage? Is it a good or bad idea to shut it off? Well my engine actually last a lot longer and will I be guaranteed do not have any lifter issues if I turn it off? Any advice would be greatly appreciated. The thing is I don’t want to ruin my engine but I also want to get the best mileage per gallon as possible.

That's allot of questions.

1.) The difference in mpg is about 10%. Is that a good thing for you?

2.) It does NOT wreck you head and piston.

3.) A few fail not all and I'll circle back to this.

4.) Turning it off does NOT mean it can not fail if it was going to.

Okay some fail. Some fail repeatedly. MOST do not. Most of this has to do with choices the owner makes about lubrication.

Hint: Very few V6 lifters fail and they use the EXACT same parts and the V8's. These motors use 5W30 instead of 0W20. Fact is I know of zero V6 lifter failures and neither does my mechanic. But he's done a few V8's.

This is a hydraulic system. They do not like AEROATION. They need to be VERY clean. Use a good oil, change is more often and be happy. Cadillac Luke (a member here) has WELL over 200K on his without issues and that boy drives.

16LT4 · July 16, 2022

22-24 mpg with a chip is what these (unmolested) get stock. My ‘16 5.3 has averaged 30.4 mpg over the last 100k miles on stock engine management software and valvetrain hardware.

KARNUT · July 16, 2022

3 hours ago, 16LT4 said:

22-24 mpg with a chip is what these (unmolested) get stock. My ‘16 5.3 has averaged 30.4 mpg over the last 100k miles on stock engine management software and valvetrain hardware.

Really! Really? That’s better than my CRV?????,,

Edited July 16, 2022 by KARNUT

DominatorZ71 · July 16, 2022

2 hours ago, 16LT4 said:

22-24 mpg with a chip is what these (unmolested) get stock. My ‘16 5.3 has averaged 30.4 mpg over the last 100k miles on stock engine management software and valvetrain hardware.

Not to call you bluff, but there's no way in hell. Must be going down hill a lot.

JimCost2014 · July 16, 2022

He travels to work and back home going downhill in both directions, wait a second.....

16LT4 · July 20, 2022

On 7/16/2022 at 11:46 AM, DominatorZ71 said:

Not to call you bluff, but there's no way in hell. Must be going down hill a lot.

Call my bluff all you want, I only report actual data.

That number is based on the dash gauge which has NEVER differed more than 1mpg from odometer-gallons math, which isn't perfect either. Folks say E85 sucks fuel mileage, yet I seem to do in the 20s on that. 22 mpg on $2.99/gallon fuel these days is a winner.

16LT4 · July 20, 2022

On 7/16/2022 at 4:15 PM, JimCost2014 said:

He travels to work and back home going downhill in both directions, wait a second.....

No, just 200 miles each way to work. And, occasionally (like a few times a year) to the Keys, because I don't like to work too much.

16LT4 · July 20, 2022

On 7/16/2022 at 11:20 AM, KARNUT said:

Really! Really? That’s better than my CRV?????,,

I'm not surprised. My 442 runs over 20mpg on the highway. We just got back to NY from a couple weeks at our house in the OBX with a loaded '22 Pacifica minivan with 3.6 Pentastar V6 (7 people and all their cra... er, luggage, including some sitting on the luggage rack hanging off the trailer hitch I'd installed for the trip), and we averaged over 28 mpg over the entire mileage of the trip. Straight out on the highway at 75 mpg, we did 34 mpg for a few hundred miles at a pop. Decent mileage isn't hard.

DominatorZ71 · July 20, 2022

35 minutes ago, 16LT4 said:

Call my bluff all you want, I only report actual data.

That number is based on the dash gauge which has NEVER differed more than 1mpg from odometer-gallons math, which isn't perfect either. Folks say E85 sucks fuel mileage, yet I seem to do in the 20s on that. 22 mpg on $2.99/gallon fuel these days is a winner.

I'm not buying it. The most I'd take your word for is 28 even that's a stretch. Take a picture of your dash last 400 miles average.

16LT4 · July 20, 2022

14 hours ago, DominatorZ71 said:

I'm not buying it. The most I'd take your word for is 28 even that's a stretch. Take a picture of your dash last 400 miles average.

Well, ya got me. The 30.4 lifetime mpg figure was from last summer's Onstar report, which I hadn't looked at until today. At 80k miles, I upgraded from stock 17" wheels to 18" wheels and larger (stock size) tires, so the odometer (and reported fuel economy) has under-read for 20% of its life. At 90k miles, I replaced those all season tires with a more aggressive all-terrain tire, and since that time, have added a 1" level and bull bar. I also drove the truck much more this past winter than normal (including towing a car), including E85 for much of it; below 60*F, I do notice a 3 mpg drop in fuel mileage with E85 compared to high summer temps. As such, lifetime mileage has dropped off considerably, the dang fuel sucking pig! I reset the 25, 50, and 400 mile mpg displays each year to track them, but they're still doing alright. I have no desire to go back to 17" low-rolling-resistance all-seasons.

The truck is still falling behind the mileage what my '14 Ram Laramie 1500 crew cab 4x4 got with the 5.7 and 3.92 towing rear; once I switched all driveline fluids over to Redline FS, I was routinely averaging 28 mpg on my 40-mile-roundtrip work commute (no highway, only local country roads), and make it from NY to our house in Kitty Hawk on a single tank, with over a quarter-tank remaining, 496 miles.

Looking at the pictures reminds me that I need to clean this filthy pig too! Dust!

Edited July 20, 2022 by 16LT4

DominatorZ71 · July 20, 2022

2 hours ago, 16LT4 said:

Well, ya got me. The 30.4 lifetime mpg figure was from last summer's Onstar report. At 80k miles, I upgraded from stock 17" wheels to 18" wheels and larger (stock size) tires, so the odometer (and reported fuel economy) has under-read for 20% of its life. At 90k miles, I replaced those all season tires with a more aggressive all-terrain tire, and since that time, have added a 1" level and bull bar. I also drove the truck much more this past winter than normal (including towing a car), including E85 for much of it; below 60*F, I do notice a 3 mpg drop in fuel mileage with E85 compared to high summer temps. As such, lifetime mileage has dropped off considerably, the dang fuel sucking pig! I reset the 25, 50, and 400 mile mpg displays each year to track them, but they're still doing alright. I have no desire to go back to 17" low-rolling-resistance all-seasons.

The truck is still falling behind the mileage what my '14 Ram Laramie 1500 crew cab 4x4 got with the 5.7 and 3.92 towing rear; once I switched all driveline fluids over to Redline FS, I was routinely averaging 28 mpg on my 40-mile-roundtrip work commute (no highway, only local country roads), and make it from NY to our house in Kitty Hawk on a single tank, with over a quarter-tank remaining, 496 miles.

Looking at the pictures reminds me that I need to clean this filthy pig too! Dust!

Ahh that's more like it! Yeah my best average on my 2017 Tahoe says 34MPG but the most I squeezed lately is 28. Which I'm still extremely happy with for a full size V8 SUV

16LT4 · July 20, 2022

2 hours ago, DominatorZ71 said:

Ahh that's more like it! Yeah my best average on my 2017 Tahoe says 34MPG but the most I squeezed lately is 28. Which I'm still extremely happy with for a full size V8 SUV

I hadn't looked at the lifetime mileage in a year, and today noticed that it has gone down in that time due to the changes I've done to the truck. 28 is great for a full-size SUV. The 400 mile average of 24 mpg was also only within the last year, not since new. Based on the lifetime mileage, I don't think the PO used E85 and likely stuck to the goldilocks zone of 50 mph roads. If I used 89 fuel, went back to lower-resistance tires, stock aero, and didn't tow-haul what I am currently, I'd get the lifetime mileage (and all the other displays) back up. From the displays, you can see the "bests" of the last year; current numbers are low due to hauling a 2000 lbs of firewood, and sand/gravel on the current tank. I've also only been locally driving the truck with stop-and-go and haven't done a good highway trip with it in a while.

So: at 90k miles, the lifetime was 30.4 mpg. Now at 102k miles, the lifetime is 26 mpg. also don't forget, those figures are also under-reported, as I didn't have the speedometer corrected when I added the bigger tires; it is off by a few mph compared to GPS. So, the 26 is more like 27 mpg. And that's on E85 for the last 3+ years.

Edited July 20, 2022 by 16LT4